Some stores were so concerned by the covert attacks that they called the police.

One of the men responsible for making stickers Kaj McBeth denied placing them in supermarkets but said he didn't believe he was doing anything wrong.

"The way I look at it, I am not doing anything illegal. Whether people want to stick them in places is up to them, I am happy to facilitate that choice if you choose to make it," Mr McBeth told The Daily Telegraph.